Hemangiopericytoma of the posterior fossa: case report

Hemangiopericytoma is an uncommon mesenchymal neoplasm arising from Zimmerman's pericytes, which usually locates in soft tissues. Meningeal hemangiopericytoma accounts for less than 1% of all intracranial tumours. Typically, it behaves aggressively, showing distinct tendency to recur locally or distantly along the neural axis and to present extraneural metastases. We describe a 74-year-old patient who presented unspecific symptoms and whose physical exam revealed a painless retroauricular mass which was adhered to skin. Neuroimaging studies showed a large posterior fossa tumour with intense enhancement after contrast infusion that caused striking occipital-mastoid osteolysis and which was exclusively fed by external carotid artery branches. The patient underwent gross total resection of the tumour, and once the histological diagnosis of hemangiopericytoma was confirmed, she underwent initial adjuvant radiotherapy. Sixteen months after surgery, the patient remains recurrence free. The treatment of choice of intracranial hemangiopericytoma is gross total resection, which must be attempted when technically feasible, followed by adjuvant radiotherapy providing total doses over 50 Gy. This combination has demonstrated increasing recurrence- free interval in these patients. Close and longterm follow-up is mandatory in order to achieve early diagnosis of recurrence or metastases in these patients, since they can appear several years, even decades, after initial proper treatment.     

Arachnoid cyst of the posterior fossa

Arachnoid cysts of the posterior fossa are uncommon. Our case of a 49-year-old man presented with a 2 month history of headaches, nausea, and vertigo associated with walking instability. An MRI revealed a median well-circumscribed cystic lesion of the posterior fossa, with similar signal characteristics to CSF, and without connection to the fourth ventricle. This aspect suggested either arachnoid or hydatid cysts. Direct open surgery was performed allowing complete removal of the cyst wall, with a good outcome.     

Ganglioglioneurocytoma of the posterior fossa.

OBJECTIVE AND IMPORTANCE: Ganglioglioneurocytoma is not yet a well defined clinical and histopathological entity; recent reports outline the histopathological features of this very rare trimorphous tumor, under different names with its basic components of gangliocytoma, neurocytoma and glioma. Four previous reports described this tumor in eleven patients. This is the first case report describing ganglioglioneurocytoma in the posterior fossa. CLINICAL PRESENTATION AND INTERVENTION: A 31-year old male with midline posterior fossa ganglioglioneurocytoma is described, providing the neuroimages and histopathological studies. CONCLUSION: Ganglioglioneurocytoma is a rare mixed neuronal and glial tumor that can also occur in the posterior fossa.     

Dermoid cyst of the posterior fossa

Intracranial dermoid tumors represent a rare clinical entity accounting for 0.1-0.7% of all intracranial tumors. Their location in the posterior fossa is uncommon. We report a 16-year-old male patient who presented with clinical signs of increased intracranial pressure and cerebellar symptoms. The CT scan revealed a median cystic lesion of the fourth ventricle causing an active triventicular hydrocephalus. The MRI showed a median well shaped cystic lesion, of low signal intensity compared to the CSF, with capsular contrast enhancement. He underwent endoscopic third ventriculostomy before subtotal removal of the lesion. The postoperative course was uneventful, and the histological diagnosis was a dermoid cyst. Through this observation, we aim to discuss the clinical, and radiological aspects of the posterior fossa dermoid cyst, and to review the therapeutic strategies.     

Teratoma of the posterior cranial fossa

Two cases of posterior cranial fossa teratomas are reported. The rarity of these lesions is stressed. In the material of surgically treated cases of brain tumours from a period of 12 years in only two patients teratomas of this location were found. In adults they are extremely rare. In both cases teratoma finding during the operation was a surprise for the neurosurgeons and this was confirmed by literature reports.     

Congenital cavities of the posterior fossa

Summary Two cysts adjacent to the recessus lateralis, but without any connection with the latter, are described. The first was found at the autopsy of a female psychiatric patient of 54 years, who had died of a cerebrovascular accident. The second case, was that of a man 61 years old. The neurosurgeon, after performing bilateral trephination for an acute hydrocephalus had found, a cyst of the right tonsil of the cerebellum.The author supposes that in these cases parts of the original roof-plate had persisted latero-ventrally to the cerebellum. The cysts first described byKramer were also thought to originate from this tissue. Some other abnormal cavities and curious cerebellar defects are described in connection with these two cases.

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Zusammenfassung Zwei dem Recessus lateralis anliegende, mit diesem jedoch nicht verbundene Cysten werden beschrieben. Die erste fand sich autoptisch bei einer psychiatrischen Patientin von 54 Jahren, die an einem cerebrovasculären Zwischenfall starb. Im zweiten Fall, einem 61 jährigen Mann, hatte der Neurochirung bei bilateraler Trepanation wegen eines akuten Hydrocephalus eine Cyste der rechten Kleinhirntonsille gefunden.Der Verfasser vermutet, daß in diesen Fällen Teile der ursprünglichen Flügelplatte ventrolateral vom Kleinhirn persistierten. Die erstmals vonKramer beschriebenen Cysten wurden ebenso dieser Anlage zugeschrieben. In Verbindung mit diesen Beobachtungen werden einige andere abnorme Höhlen und merkwürdige Defekte des Kleinhirns beschrieben.

     

Neuroanatomy of fragile X syndrome: the posterior fossa

The occurrence and specificity of posterior fossa abnormalities as measured from magnetic resonance images of the brain were investigated in a group of 14 males with fragile X syndrome and comparison groups consisting of 17 males with other causes of developmental disability and 18 males with normal IQs. The size of the posterior cerebellar vermis was significantly decreased and the fourth ventricle significantly increased in the group of males with fragile X syndrome compared with males in both comparison groups. These neuroanatomical abnormalities appeared to be secondary to hypoplasia rather than atrophy.     

Haemangioblastoma of the posterior cranial fossa: clinico-neuropathological study

Haemangioblastoma (HBs) may occur sporadically in the central nervous system, or in association with von Hippel-Lindau (VHL) disease. Haemangioblastoma of the central nervous system is often seen in the posterior cranial fossa. VHL is an autosomaly dominant disorder. In sporadic HBs tumours, VHL alleles are reported to be inactive in up to 50% of tumours. Five patients with tumours of the posterior cranial fossa were examined by scyntygrapghy, computed tomography or magnetic resonance imaging (MRI). Metastases were initially diagnosed by neuroimaging examinations in two patients, and HBs in the remaining cases. In four patients, tumours were removed neurosurgically. Two patients had evidence of VHL disease. All resected tumours and autopsy materials were studied histologically and immunohistologically. Most antibodies that were used showed positive immunoreactions with stromal, endothelial, and pericyte or macrophage cells in tumours diagnosed as haemangioblastoma. Preoperative diagnosis of haemangioblastoma is mostly precise with MRI or magnetic resonance angiograghy. The surgical treatment of HBs is only a part of the complex therapeutical process. Diagnosis based on the gene analysis can be very useful in early detection or protection against potential recurrence of this disease in patients and their families.     

Traumatic posterior fossa hematoma

The traumatic posterior fossa hematoma was regarded as relatively rare thing, but recently, as the result of the prevalence of CT scanners, the number of reported cases is increasing. We report nine cases of traumatic posterior fossa hematoma. We divided into two categories: one was the acute epidural hematoma, the other was the acute subdural hematoma with cerebellar contusion. Five were cases of the acute epidural hematoma, three were cases of the acute subdural hematoma with cerebellar contusion and a case had both an epidural and a subdural hematoma. All the cases had struck the occipital region and had the occipital bone fracture. The prognosis of the five cases of the acute epidural hematoma was excellent, but that of the four cases of the acute subdural hematoma with cerebellar contusion was poor and they all died inspite of the removal of the hematoma executed in three cases. We estimated that the hitting forth was extremely strong in cases of the subdural hematoma with cerebellar contusion, and that the momentary deformity of the occipital bone might injure the cerebellum directly. Once a hematoma was produced in the posterior fossa, it oppresses the brainstem and causes the acute hydrocephalus, so the state of consciousness and respiration deteriorate suddenly. In cases of the acute epidural hematoma, appropriate surgical intervention could save the patients and resulted in good outcome. But in some cases of the fulminant type acute epidural hematoma of the posterior fossa caused by tearing the sinuses, though we have not experienced, patients die before the diagnosis and treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Giant posterior fossa teratoma

In this study we report a rare case of a giant midline posterior fossa teratoma; its clinical presentation, radiological appearance, treatment and outcome, with an extensive review of the literature. Received: 7 December 1998 Revised: 22 March 1999